McqMate
| 1. |
The main function of a fuse is to |
| A. | protect the line |
| B. | open the circuit |
| C. | protect the appliance |
| D. | prevent excessive currents |
| Answer» D. prevent excessive currents | |
| 2. |
On which of the following routine tests are conducted? |
| A. | Oil circuit breakers |
| B. | Air blast circuit breakers |
| C. | Minimum oil circuit breakers |
| D. | All of the above |
| Answer» D. All of the above | |
| 3. |
SF6 gas |
| A. | is yellow in colour |
| B. | is lighter than air |
| C. | is nontoxic |
| D. | has pungent small |
| Answer» C. is nontoxic | |
| 4. |
The arcing contacts in a circuit breaker are made of |
| A. | copper tungsten alloy |
| B. | porcelain |
| C. | electrolytic copper |
| D. | aluminium alloy |
| Answer» A. copper tungsten alloy | |
| 5. |
Which of the following medium is employed for extinction of arc in air circuit breaker ? |
| A. | Water |
| B. | Oil |
| C. | Air |
| D. | SF6 |
| Answer» C. Air | |
| 6. |
With which of the following, a circuit breaker must be equipped for remote operation ? |
| A. | Inverse time trip |
| B. | Time-delay trip |
| C. | Shunt trip |
| D. | None of the above |
| Answer» C. Shunt trip | |
| 7. |
Fault diverters are basically |
| A. | fuses |
| B. | relays |
| C. | fast switches |
| D. | circuit breakers |
| Answer» C. fast switches | |
| 8. |
A thermal protection switch can protect against |
| A. | short-circuit |
| B. | temperature |
| C. | overload |
| D. | over voltage |
| Answer» C. overload | |
| 9. |
Arc in a circuit behaves as |
| A. | a capackive reactance |
| B. | an inductive reactance |
| C. | a resistance increasing with voltage rise across the arc |
| D. | a resistance decreasing with voltage rise across the arc |
| Answer» D. a resistance decreasing with voltage rise across the arc | |
| 10. |
Thermal circuit breaker has |
| A. | delayed trip action |
| B. | instantaneous trip action |
| C. | both of the above |
| D. | none of the above |
| Answer» A. delayed trip action | |
| 11. |
Relays can be designed to respond to changes in |
| A. | resistance, reactance or impedance |
| B. | voltage and current |
| C. | light intensity |
| D. | all above |
| Answer» D. all above | |
| 12. |
Overload relays are of…… type. |
| A. | induction |
| B. | solid state |
| C. | thermal |
| D. | all above |
| Answer» D. all above | |
| 13. |
Thermal overload relays are used to protect the motor against over current due to |
| A. | short-circuits |
| B. | heavy loads |
| C. | grounds |
| D. | all of the above |
| Answer» B. heavy loads | |
| 14. |
Magnetic circuit breaker has ______ trip action. |
| A. | delayed |
| B. | instantaneous |
| C. | both of the above |
| D. | none of the above |
| Answer» B. instantaneous | |
| 15. |
D.C. shunt relays are made of |
| A. | few turns of thin wire |
| B. | few turns of thick wire |
| C. | many turns of thin wire |
| D. | many turns of thick wire |
| Answer» C. many turns of thin wire | |
| 16. |
The relay operating speed depends upon |
| A. | the spring tension |
| B. | the rate of flux built up |
| C. | armature core air gap |
| D. | all of the above |
| Answer» D. all of the above | |
| 17. |
In order that current should flow without causing excessive heating or voltage drop, the relay contacts should |
| A. | have low contact resistance |
| B. | be clean and smooth |
| C. | be of sufficient size and proper shape |
| D. | have all above properties |
| Answer» D. have all above properties | |
| 18. |
Circuit breakers usually operate under |
| A. | transient state of short-circuit current |
| B. | sub-transient state of short-circuit current |
| C. | steady state of short-circuit current |
| D. | after D.C. component has ceased |
| Answer» A. transient state of short-circuit current | |
| 19. |
Circuit breakers are essentially |
| A. | current carrying contacts called electrodes |
| B. | arc extinguishers |
| C. | circuits to break the system |
| D. | tr |
| Answer» A. current carrying contacts called electrodes | |
| 20. |
The current zero interruption, in oil and air blast circuit breakers, is achieved by |
| A. | lengthening of the gap |
| B. | cooling and blast effect |
| C. | both (a) and (b) |
| D. | deionizing the oil with forced air |
| Answer» C. both (a) and (b) | |
| 21. |
Air blast circuit breaker is used for |
| A. | over currents |
| B. | short duty |
| C. | intermittant duty |
| D. | repeated duty |
| Answer» D. repeated duty | |
| 22. |
An efficient and a well designed protective relaying should have |
| A. | good selectivity and reliability |
| B. | economy and simplicity |
| C. | high speed and selectivity |
| D. | all of the above |
| Answer» D. all of the above | |
| 23. |
Burden of a protective relay is the power |
| A. | required to operate the circuit breaker |
| B. | absorbed by the circuit of relay |
| C. | developed by the relay circuit |
| D. | none of the above |
| Answer» B. absorbed by the circuit of relay | |
| 24. |
Directional relays are based on flow of |
| A. | power |
| B. | current |
| C. | voltage wave |
| D. | all of the above |
| Answer» A. power | |
| 25. |
A differential relay measures the vector difference between |
| A. | two currents |
| B. | two voltages |
| C. | two or more similar electrical quantities |
| D. | none of the above |
| Answer» C. two or more similar electrical quantities | |
| 26. |
A transmission line is protected by |
| A. | inrush protection |
| B. | distance protection |
| C. | time graded and current graded over current protection |
| D. | both (b) and (c) |
| Answer» D. both (b) and (c) | |
| 27. |
Large internal faults are protected by |
| A. | merz price percentage differential protection |
| B. | mho and ohm relays |
| C. | horn gaps and temperature relays |
| D. | earth fault and positive sequence relays |
| Answer» A. merz price percentage differential protection | |
| 28. |
When a transmission line is energized, the wave that propagates on it is |
| A. | current wave only |
| B. | voltage wave only |
| C. | both (a) and (b) |
| D. | power factor wave only |
| Answer» C. both (a) and (b) | |
| 29. |
Protective relays are devices that detect abnormal conditions in electrical circuits by measuring |
| A. | current during abnormal condition |
| B. | voltage during abnormal condition |
| C. | constantly the electrical quantities which differ during normal and abnormal conditions |
| D. | none of the above |
| Answer» C. constantly the electrical quantities which differ during normal and abnormal conditions | |
| 30. |
The voltage appearing across the contacts after opening of the circuit breaker is called______voltage. |
| A. | recovery |
| B. | surge |
| C. | operating |
| D. | arc |
| Answer» A. recovery | |
| 31. |
Ionization in circuit breaker is facilitated by |
| A. | high temperature |
| B. | increase of mean free path |
| C. | increasing field strength |
| D. | all of the above |
| Answer» D. all of the above | |
| 32. |
In a circuit breaker the basic problem is to |
| A. | maintain the arc |
| B. | extinguish the arc |
| C. | transmit large power |
| D. | emit the ionizing electrons |
| Answer» C. transmit large power | |
| 33. |
Overheating of relay contacts or contact born out is due to |
| A. | slow making and breaking of load circuit contacts |
| B. | foreign matter on the contact surface |
| C. | too low contact pressure |
| D. | all of the above |
| Answer» D. all of the above | |
| 34. |
Interruption of large currents by relay requires |
| A. | arc suppressing blow out coils |
| B. | wide separation of the opened contacts |
| C. | high speed opening of contacts |
| D. | all of the above |
| Answer» D. all of the above | |
| 35. |
Shunt capacitance is neglected while considering |
| A. | short transmission line |
| B. | medium transmission line |
| C. | long transmission line |
| D. | medium and long tr |
| Answer» A. short transmission line | |
| 36. |
The arc voltage produced in A.C. circuit breaker is always |
| A. | in phase with the arc current |
| B. | lagging the arc current by 90″ |
| C. | leading the arc current by 90° |
| D. | none of the above |
| Answer» A. in phase with the arc current | |
| 37. |
The time of closing the cycle, in modern circuit breakers is |
| A. | 0.003 sec |
| B. | 0.001 sec |
| C. | 0.01 sec |
| D. | 0.10 sec |
| Answer» A. 0.003 sec | |
| 38. |
Insulation resistance of high voltage circuit breakers is more than |
| A. | 1 mega ohms |
| B. | 10 mega ohms |
| C. | 100 mega ohms |
| D. | 500 mega ohms |
| Answer» C. 100 mega ohms | |
| 39. |
H.R.C. fuses provide best protection against |
| A. | overload |
| B. | reverse current |
| C. | open-circuits |
| D. | short-circuits |
| Answer» D. short-circuits | |
| 40. |
The ground wire should not be smaller than No ______ copper. |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 10 |
| Answer» D. 10 | |
| 41. |
The delay fuses are used for the protection of ________ . |
| A. | motors |
| B. | power outlet circuits |
| C. | fluorescent lamps |
| D. | light circuits |
| Answer» A. motors | |
| 42. |
Which of the following is the least expensive protection for overcurrent is low voltage system ? |
| A. | Rewireable fuse |
| B. | Isolator |
| C. | Oil circuit breaker |
| D. | Air break circuit breaker |
| Answer» A. Rewireable fuse | |
| 43. |
Resistance grounding is used for voltage between |
| A. | 33kVto66kV |
| B. | HkVto33kV |
| C. | 3.3kVandllkV |
| D. | none of the above |
| Answer» C. 3.3kVandllkV | |
| 44. |
The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to |
| A. | lubricate the contacts |
| B. | insulate the contacts from switch body |
| C. | extinguish the arc |
| D. | all of the above |
| Answer» C. extinguish the arc | |
| 45. |
In Railway applications ______ circuit breaker is used. |
| A. | SFe |
| B. | bulk oil |
| C. | minimum oil |
| D. | air break |
| Answer» D. air break | |
| 46. |
To protect most of the electrical equipment handling low power, the types of relays used are |
| A. | thermocouple |
| B. | electronic and bimetallic |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» C. both (a) and (b) | |
| 47. |
Wave trap is used to trap waves of |
| A. | power frequencies |
| B. | higher frequencies entering generator or transformer units |
| C. | either of the above |
| D. | none of the above |
| Answer» B. higher frequencies entering generator or transformer units | |
| 48. |
Ungrounded neutral transmission system is not recommended because of system |
| A. | insulation being overstressed due to over voltages |
| B. | insulation overstress may lead to failure and subsequent phase to phase faults |
| C. | being inadequately protected against ground fault |
| D. | all of the above |
| Answer» D. all of the above | |
| 49. |
The reflection co-efficient at the open circuited end of a transmission line. |
| A. | zero |
| B. | infinity |
| C. | unity |
| D. | none of the above |
| Answer» C. unity | |
| 50. |
For the protection of power station buildings against direct strokes the requirements are |
| A. | interception |
| B. | interception and conduction |
| C. | interception, conduction and dissipation |
| D. | interception, conduction, dissipation and reflection |
| Answer» C. interception, conduction and dissipation | |
| 51. |
The line insulation is the insulation level of the station equipment. |
| A. | less than |
| B. | same as |
| C. | more than |
| D. | not directly related with |
| Answer» D. not directly related with | |
| 52. |
The interaction between a transmission line and communication line is minimized by |
| A. | transposing transmission as well as communication lines |
| B. | increasing the height of the trans-mission line tower |
| C. | increasing the distance between the two lines |
| D. | all of the above |
| Answer» D. all of the above | |
| 53. |
When a wave propagates on a transmission line, it suffers reflection several times at |
| A. | tapping |
| B. | load end |
| C. | sending end |
| D. | sending and other end |
| Answer» D. sending and other end | |
| 54. |
Which of the following statements is incorrect? |
| A. | Station batteries are used to operate relay only |
| B. | The lightning arresters are basically surge diverters |
| C. | An impedance relay has maximum fault current when fault occurs near the relay |
| D. | A high speed relay has an operation of 1 to 2 cycles |
| Answer» A. Station batteries are used to operate relay only | |
| 55. |
Discrimination between main and back up protection is provided by the use of relays which are |
| A. | fact |
| B. | sensitive |
| C. | slow |
| D. | none of the above |
| Answer» C. slow | |
| 56. |
Induction cup relay is operated due to changes in |
| A. | current |
| B. | voltage |
| C. | impedance |
| D. | all of the above |
| Answer» D. all of the above | |
| 57. |
A.C. network analyser is used to solve problems of |
| A. | load flow |
| B. | load flow and short-circuit |
| C. | load flow and stability |
| D. | load flow, short-circuit and stability |
| Answer» D. load flow, short-circuit and stability | |
| 58. |
Which of the following statements is incorrect ? |
| A. | Lightning arrestors are used before the switchgear |
| B. | Shunt reactors are used as compensation reactors |
| C. | The peak short current is (1.8 xV2) times the A.C. component |
| D. | The MVA at fault is equal to base MVA divided by per unit equivalent fault reactance |
| Answer» A. Lightning arrestors are used before the switchgear | |
| 59. |
Short-circuit currents are due to |
| A. | single phase to ground faults |
| B. | phase to phase faults |
| C. | two phase to ground faults |
| D. | any of these |
| Answer» D. any of these | |
| 60. |
To reduce short circuit fault currents are used. |
| A. | reactors |
| B. | resistors |
| C. | capacitors |
| D. | none of the above |
| Answer» A. reactors | |
| 61. |
Bus coupler is very essential in arrangement |
| A. | single bus |
| B. | double bus, double breaker |
| C. | main and transfer bus |
| D. | all of the above |
| Answer» C. main and transfer bus | |
| 62. |
For cost and safety, the outdoor substations are installed for voltages above |
| A. | 11 kV |
| B. | 33 kV |
| C. | 60kV |
| D. | 110kV |
| Answer» B. 33 kV | |
| 63. |
The short circuit in any winding of the transformer is the result of |
| A. | mechanical vibration |
| B. | insulation failure |
| C. | loose connection |
| D. | impulse voltage |
| Answer» D. impulse voltage | |
| 64. |
relays are used for phase faults on long line. |
| A. | Impedance |
| B. | Reactance |
| C. | Either of the above |
| D. | None of the above |
| Answer» A. Impedance | |
| 65. |
For which of the following protection from negative sequence currents is provided? |
| A. | Generators |
| B. | Motors |
| C. | Transmission line |
| D. | Tr |
| Answer» A. Generators | |
| 66. |
relay is preferred for phase fault on short transmission line. |
| A. | Induction type |
| B. | Reactance |
| C. | Impedance |
| D. | None of the above |
| Answer» B. Reactance | |
| 67. |
Distance relays are generally |
| A. | split-phase relays |
| B. | reactance relays |
| C. | impedance relays |
| D. | none of the above |
| Answer» D. none of the above | |
| 68. |
For which of the following ratings of the transformer differential protection is recommended ? |
| A. | above 30 kVA. |
| B. | equal to and above 5 MVA |
| C. | equal to and above 25 MVA |
| D. | none of the above |
| Answer» B. equal to and above 5 MVA | |
| 69. |
A _______ is used to measure the stator % winding temperature of the generator. |
| A. | thermocouple |
| B. | pyrometer |
| C. | resistance thermometer |
| D. | thermometer |
| Answer» C. resistance thermometer | |
| 70. |
The under voltage relay can be used for |
| A. | generators |
| B. | busbars |
| C. | transformers |
| D. | all of the above |
| Answer» D. all of the above | |
| 71. |
The relay with inverse time characteristic will operate within |
| A. | 1.5 sec |
| B. | 5 to 10 sec |
| C. | 5 to 20 sec |
| D. | 20 to 30 sec |
| Answer» B. 5 to 10 sec | |
| 72. |
The single phasing relays are used for the protection of |
| A. | single phase motors only |
| B. | two phase motors only |
| C. | two single phase motors running in parallel |
| D. | three phase motors |
| Answer» D. three phase motors | |
| 73. |
Which of the following devices will receive voltage surge first travelling on the transmission line ? |
| A. | Lightning arresters |
| B. | Relays |
| C. | Step-down transformer |
| D. | Switchgear |
| Answer» A. Lightning arresters | |
| 74. |
Which of the following parameter can be neglected for a short line ? |
| A. | Inductance |
| B. | Capacitance |
| C. | Resistance |
| D. | Reactance |
| Answer» B. Capacitance | |
| 75. |
Series reactors should have |
| A. | low resistance |
| B. | high resistance |
| C. | low impedance |
| D. | high impedance |
| Answer» A. low resistance | |
| 76. |
Which of the following circuit breakers has high reliability and minimum maintenance ? |
| A. | Air blast circuit breakers |
| B. | Circuit breaker with SF6 gas |
| C. | Vacuum circuit breakers |
| D. | Oil circuit breakers |
| Answer» B. Circuit breaker with SF6 gas | |
| 77. |
Arc in a circuit breaker is interrupted at |
| A. | zero current |
| B. | maximum current |
| C. | minimum voltage |
| D. | maximum voltage |
| Answer» A. zero current | |
| 78. |
transmission line has reflection coefficient as one. |
| A. | Open circuit |
| B. | Short-circuit |
| C. | Long |
| D. | None of the above |
| Answer» A. Open circuit | |
| 79. |
What will be the reflection co-efficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ? |
| A. | Zero |
| B. | Unity |
| C. | Infinity |
| D. | None of the above |
| Answer» A. Zero | |
| 80. |
The inverse definite mean time relays are used for over current and earth fault protection of transformer against |
| A. | heavy loads |
| B. | internal short-circuits |
| C. | external short-circuits |
| D. | all of the above |
| Answer» B. internal short-circuits | |
| 81. |
Over voltage protection is recommended for |
| A. | hydro-electric generators |
| B. | steam turbine generators |
| C. | gas turbine generators |
| D. | all of the above |
| Answer» D. all of the above | |
| 82. |
Air blast circuit breakers for 400 kV power system are designed to operate in |
| A. | 100 microsecond |
| B. | 50 millisecond |
| C. | 0.5 sec |
| D. | 0.1 sec |
| Answer» B. 50 millisecond | |
| 83. |
Overfluxing protection is recommended for |
| A. | distribution transformer |
| B. | generator transformer of the power plant |
| C. | auto-transformer of the power plant |
| D. | station tr |
| Answer» A. distribution transformer | |
| 84. |
Series capacitors are used to |
| A. | compensate for line inductive reactance |
| B. | compensate for line capacitive reactance |
| C. | improve line voltage |
| D. | none of the above |
| Answer» A. compensate for line inductive reactance | |
| 85. |
Admittance relay is _______ relay. |
| A. | impedance |
| B. | directional |
| C. | non-directional |
| D. | none of the above |
| Answer» B. directional | |
| 86. |
The material used for fuse must have |
| A. | low melting point and high specific resistance |
| B. | low melting point and -low specific resistance |
| C. | high melting point and low specific resistance |
| D. | low melting point and any specific resistance |
| Answer» A. low melting point and high specific resistance | |
| 87. |
If the fault occurs near the impedance relay, the VII ratio will be |
| A. | constant for all distances |
| B. | lower than that of if fault occurs away from the relay |
| C. | higher than that of if fault occurs away from the relay |
| D. | none of the above |
| Answer» B. lower than that of if fault occurs away from the relay | |
| 88. |
The torque produced in induction type relay (shaded pole structure) is |
| A. | inversely proportional to the current |
| B. | inversely proportional to the square of the current |
| C. | proportional to the current |
| D. | proportional to square of the current |
| Answer» B. inversely proportional to the square of the current | |
| 89. |
The steady state stability of the power system can be increased by |
| A. | connecting lines in parallel |
| B. | connecting lines in series |
| C. | using machines of high impedance |
| D. | reducing the excitation of machines |
| Answer» A. connecting lines in parallel | |
| 90. |
The inductive interference between power and communication line can be minimized by |
| A. | transposition of the power line |
| B. | transposition of the communication line |
| C. | both (a) and (b) |
| D. | increasing the distance between the conductors |
| Answer» C. both (a) and (b) | |
| 91. |
The power loss is an important factor for the design of |
| A. | transmission line |
| B. | motor |
| C. | generator |
| D. | feeder |
| Answer» A. transmission line | |
| 92. |
A fuse is connected |
| A. | in series with circuit |
| B. | in parallel with circuit |
| C. | either in series or in parallel with circuit |
| D. | none of the above |
| Answer» A. in series with circuit | |
| 93. |
H.R.C. fuse, as compared to a rewirable fuse, has |
| A. | no ageing effect |
| B. | high speed of operation |
| C. | high rupturing capacity |
| D. | all of the above |
| Answer» D. all of the above | |
| 94. |
The fuse rating is expressed in terms of |
| A. | current |
| B. | voltage |
| C. | VAR |
| D. | kVA |
| Answer» A. current | |
| 95. |
The fuse blows off by |
| A. | burning |
| B. | arcing |
| C. | melting |
| D. | none of the above |
| Answer» C. melting | |
| 96. |
On which of the following effects of electric current a fuse operates ? |
| A. | Photoelectric effect |
| B. | Electrostatic effect |
| C. | Heating effect |
| D. | Magnetic effect |
| Answer» C. Heating effect | |
| 97. |
An isolator is installed |
| A. | to operate the relay of circuit breaker |
| B. | as a substitute for circuit breaker |
| C. | always independent of the position of circuit breaker |
| D. | generally on both sides of a circuit breaker |
| Answer» D. generally on both sides of a circuit breaker | |
| 98. |
A fuse in a motor circuit provides protection against |
| A. | overload |
| B. | short-circuit and overload |
| C. | open circuit, short-circuit and overload |
| D. | none of the above |
| Answer» B. short-circuit and overload | |
| 99. |
Protection by fuses is generally not used beyond |
| A. | 20 A |
| B. | 50 A |
| C. | 100 A |
| D. | 200 A |
| Answer» C. 100 A | |
| 100. |
A fuse is never inserted in |
| A. | neutral wire |
| B. | negative of D.C. circuit |
| C. | positive of D.C. circuit |
| D. | phase dine |
| Answer» A. neutral wire | |
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